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Solution structures of beta peptide and its constituent fragments: relation to amyloid deposition

journal contribution
posted on 1991-07-12, 00:00 authored by Colin BarrowColin Barrow, M G Zagorski
The secondary structures in solution of the synthetic, naturally occurring, amyloid beta peptides, residues 1 to 42 [beta (1-42)] and beta (1-39), and related fragments, beta (1-28) and beta (29-42), have been studied by circular dichroism and two-dimensional nuclear magnetic resonance spectroscopy. In patients with Alzheimer's disease, extracellular amyloid plaque core is primarily composed of beta (1-42), whereas cerebrovascular amyloid contains the more soluble beta (1-39). In aqueous trifluoroethanol solution, the beta (1-28), beta (1-39), and beta (1-42) peptides adopt monomeric alpha-helical structures at both low and high pH, whereas at intermediate pH (4 to 7) an oligomeric beta structure (the probable structure in plaques) predominates. Thus, beta peptide is not by itself an insoluble protein (as originally thought), and localized or normal age-related alterations of pH may be necessary for the self-assembly and deposition of beta peptide. The hydrophobic carboxyl-terminal segment, beta(29-42), exists exclusively as an oligomeric beta sheet in solution, regardless of differences in solvent, pH, or temperature, suggesting that this segment directs the folding of the complete beta (1-42) peptide to produce the beta-pleated sheet found in amyloid plaques.

History

Journal

Science

Volume

253

Issue

5016

Pagination

179 - 182

Publisher

American Association for the Advancement of Science

Location

Washington, D.C.

ISSN

0036-8075

Language

eng

Publication classification

CN.1 Other journal article

Copyright notice

1991, American Association for the Advancement of Science

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